In what has already been a banner year for the health industry, Pfizer and Allergan are in talks over a potential mega-merger.

Pfizer is the maker of top-selling drug Viagra, while Dublin based Allergan makes Botox. Allergan is valued at $113 billion, meaning an acquisition will make it the largest in the year so far, with a slim chance of any other beating it out.

It’s been a busy year for Allergan, having been acquired by Actavis for $70.5 billion in November, with the new company retaining the name of the former. Later in the year, Allergan agreed to sell its generic drug arm to Teva Pharmaceuticals for $40.5 billion.

This would be an unprecedented three major deals by one company in the span of a year. American drug maker Pfizer has also been busy this year, though without much success. It failed in its attempt to purchase British drug-maker AstraZeneca for the second year in a row.

The deal was an attempt by Pfizer to establish a foreign base of operations, in order to relieve some of its tax burden in the US. American regulators fiercely opposed Pfizer’s initial attempt at the AstraZeneca deal and have already begun to oppose this one.